Swimming Modifications of Adult Female Hydropsychidae Compared with Other Trichoptera

Mesothoracic legs of 10 of 12 species of adult female Hydropsychidae (not Parapsyche almota or P. elsis) are modified for swimming; at least four of the ten species are known to swim to stream substrates to oviposit. Modified tibiae and tarsi of females differed from those of males in being widened, concave, and often, with a fringe of longer hair on the posterior edge. Modified mesothoracic legs were also found on some adult female Glossosomatidae, Polycentropodidae, and Psychomyiidae. Differences in swimming modifications found among hydropsychids and glossosomatids suggest a diversity of ovipositing behavior within these families.